Publication:

Effectiveness of low dose physostigmine for dose reduction of morphine in pain management

Background This is an interventional study, undertaken in the experimental animal models for the evaluation of the antinociceptive potential of Physostigmine and its combination with Morphine at their sub-analgesic doses. The objective of the study was to evaluate the antinociceptive potential of Physostigmine alone and in combination with morphine.

Methods Antinociceptive effect of Physostigmine in three graded doses (50, 100 and 200 μg/kg) and combination of Physostigmine at low dose (50 μg/kg) with sub-analgesic dose of Morphine (0.1 mg/kg) and Morphine in analgesic dose (1 mg/kg) was evaluated by using Hot Water Bath method in albino rats.

Results Comparison of maximal possible effect in percentage (MPE in %) between groups at 90 minutes in control, Morphine, Physostigmine in 50, 100, 200 μg/ kg doses and combination group respectively, demonstrated significant difference (p <0.001) when compared by one way ANOVA test. There was no much increase in maximal possible effect in the tail withdrawal latency in Physostigmine 50 μg/kg (SC) treatment at 90 min (5.50±0.88) in comparison to control (NS) treatment group. Combination treatment of low doses of both Physostigmine 50 μg/kg + Morphine 0.1 mg/kg increased in maximal possible effect the tail withdrawal latency 90 min (53.87±1.38) in-comparison to control (NS) treatment group (6.17±0.92).

Conclusions Physostigmine is more potent antinociceptive than Morphine and Physostigmine potentiated the antinociceptive activity of low dose of standard drug Morphine.